Credit

Caption

Cut-away of Earth. Computer-edited photograph of Earth, with a cut-away showing the planet's interior structure and core. Coloured zones represent different layers: inner core = white, outer core = yellow, mantle = orange and red (not to scale). The photograph of Earth was taken by the crew of the American rocket Apollo 7 during a mission to the Moon in 1972. The land-mass in the top-right is North Africa. In the centre right is the Red Sea, with Arabia and the Horn of Africa on either side.